The Chi-Square Distribution: Notation 1.3 2008/06/20 11:25:28 GMT-5 2008/07/15 10:06:55.715 GMT-5 Barbara Illowsky illowskybarbara@deanza.edu Susan Dean deansusan@deanza.edu Connexions cnx@cnx.org elementary statistics This module provides an overview of Chi-Square Distribution Notation as a part of Collaborative Statistics collection (col10522) by Barbara Illowsky and Susan Dean. The notation for the chi-square distribution is: χ 2 ~ χ df 2 where df = degrees of freedom depend on how chi-square is being used. (If you want to practice calculating chi-square probabilities then use df = n - 1 . The degrees of freedom for the three major uses are each calculated differently.)For the χ 2 distribution, the population mean is μ = df and the population standard deviation is σ = 2 ⋅ df .The random variable is shown as χ 2 but may be any upper case letter.The random variable for a chi-square distribution with k degrees of freedom is the sum of k independent, squared normal variables. χ 2 = ( Z 1 ) 2 + ( Z 2 ) 2 + ... + ( Z k ) 2